This invention relates to a centrifugal blood pump designed to be used as a cardiac assist device, and the method of using same. More particularly, this invention is an apparatus and method for reducing the maximum pressure in the right or left ventricle of the heart in synchronism with the ventricular contractions.
Centrifugal pumps used to replace or assist a failing heart are known in the prior art. It is particularly important that the natural blood of the heart be maintained. The walls of the vascular system are designed for the particular flow waveform produced by a healthy heart. The blood flow or velocity waveform during each pulsation should be such that there is no breakdown or damage to the blood or the vascular system. Devices presently now in existence either fail to duplicate the pressures and flows that would normally be expected from a healthy heart or require complex control means to establish the desired flow.
One heart assist device uses elaborate sensing means to monitor the pressure in the heart. A complex closed-loop servo-mechanism is used to operate the pump in synchronism to the sensed pressure in the heart and to maintain the programmed stolic pressure.
Another heart assist device simulates the pressure pulsations of a natural heart by either varying the speed of the pump so as to cause the output pressure to change or by running the pump at a constant speed wherein a specially designed diffuser is added to the pump. The diffuser is limited to certain time constants and pulse heights inherent in its design.